Development of a polymer-based sensing platform for the thermal detection of antimicrobial resistance

Antibiotics revolutionized modern medicine, but these 'wonder' drugs are under threat due to the rapid emergence of antimicrobial resistant bacterial strains that no longer respond to standard antibiotic treatment. This endangers current standard procedures, such as major surgery, cancer therapy and organ transplantation. Monitoring these resistant strains is key to combating them.

In this proposal, we will produce a biosensor for the detection of bacteria, particularly those with antimicrobial resistance. In a simple and low-cost manner, we can rapidly identify the source of bacterial infection to enable clinicians to develop a personalized treatment plan that will benefit patients' care.

In addition, we will expand this to an array format for the simultaneous detection of bacteria and antibiotics, which can serve to screen (food) samples for antibiotic residues and will provide valuable insight into how bacteria develop AMR properties.

We will use a technique called molecular imprinting for producing the sensor platform. These Molecularly Imprinted Polymers (MIPs) are often referred to as "plastic" antibodies. These materials have a porous structure, with high affinity binding sites for their target molecule. Their advantages over "natural" antibodies include low-cost, straightforward preparation, robustness, and ability to work in extreme environments (pH, adverse temperatures and organic solvents).

Prior work in the PI's group has shown that binding of targets to imprinted polymers can alter the conduction of heat through the polymer essentially blocking heat-flow. This can lead to a temperature differential which can be measured by a thermal sensor (thermocouple device). This change in heat-flow is dependent on target concentration. This method, patented as the Heat-Transfer Method (HTM), has only been studied with MIP microstructures. In this proposal, we will take a novel electrochemical approach to develop MIP nanolayers that will increase the sensitivity of the developed sensor platform.

This project consists of the following steps:

(a) Use of electrochemical methods to prepare MIP sensors.
We will prepare nanometre thick bacterial imprinted layers functionalised onto electrodes from five different monomers, which have been identified from literature databases to bind bacteria. Using HTM it will be determined which monomer has the highest potential to bind a particular bacterial strain allowing us to optimise the MIP. A series of medically relevant targets (including Staphylococcus aureus strains, some of which exhibit antimicrobial resistance) will be measured and the sensor performance will be optimised in terms of time, selectivity and affinity.

(b) Thermal measurements of bacterial in buffered solutions
We will perform thermal measurements with the MIP sensors (library of six bacteria) to evaluate the bacterial loads in buffered solutions. These measurements will be validated against current gold-standard techniques (ELISA, genotyping) to determine the accuracy and precision of the developed thermal sensing strategy.

(c) Thermal measurements of "complex" samples
Clinical or food samples are complex matrices - we will evaluate if we can selectively detect certain bacterial strains in the presence of an excess of other (harmless) bacteria. Finally, we will explore if we can transform this sensor into an array format for the simultaneous detection of bacteria and antibiotics, by integrating MIPs specific for antibiotic compounds.

This proposal will build the research portfolio of the PI, establish her independence, and lay the foundation of a multidisciplinary and exciting research programme. A project partner at Maastricht will provide advice on thermal measurements and serve for knowledge exchange visits. The developed sensor platform has commercial potential due to its low-cost and simplicity and the PI will explore its this during the project timeline.

There is no doubt that investigations on AMR are timely since it is considered a serious threat to global public health. Identification of the source and type of a bacterial infection is key to combating AMR. Therefore, there is a clear and compelling need to develop routine tests which can rapidly identify different bacteria and antibacterial agents in-situ. This proposal will build the foundation of a multidisciplinary research programme towards the development of a sensor array capable of this, using a low-cost and portable technology. A successful design would have high commercial potential in multiple areas of analysis. As well as the academic benefits discussed elsewhere there will be a range of impact, both in the short and longer term.

In the short term:
- Further understanding of the new HTM technique and platform;
- Development of novel MIP sensors, and evaluation of the impact of sensor architecture on thermal detection;
- The use of thermal detection methods for bacterial identification and concentrations in a range of samples;
- The use of thermal detection methods for antibiotic identification and concentrations in a range of samples;
- Proof that the HTM sensors can match, or improve on, the current "gold-standard" techniques;
- A fully operable array platform for multiple target analysis.

In the longer term:
- A simple sensor array that can be modified for other applications across the breath of analytical problems such as routine site monitoring in the food and health industries;
- Portable environmental monitoring within the water and building industries; as well as maintaining scrutiny on hygiene management;
- A proven sensor would be highly sought after in the fields of personalised medicine, reducing economic costs caused by extended hospitalization of patients;
- The application of these sensors in sustainable healthcare in both developed and developing countries;
- Potential use of these sensors in a military setting for rapid chemical and biological analysis.

The development of an array capable of detecting both bacteria and antibiotics will allow access to data that will give valuable insight into how bacteria develop AMR properties. This topic is currently poorly understood but it is known that certain parameters, such as the persistent low-level concentration of antibiotics and length of exposure, accelerate AMR development. With this technology, it would be possible to monitor this in-situ, which in the longer term will support strategies to reduce the rate at which resistance develops or potentially predict when this will occur.
There will be impact on the people associated with the project. The PDRA attached to this project will gain significant experience in a multi-disciplinary, multi-organisation project. They will have the opportunity to expand their academic portfolio through further training, publications and public engagement.
The PI and project partners will benefit from interest in this work which will bolster their reputation. As a result, they are likely to attract further investment, both nationally and internationally.
The PI will gain experience in the organisation and coordination of a multidisciplinary project. She will exploit the IP of her findings together with industrial partners that are established through networking events or via existing industrial connections of the project team. The RKE office of MMU will fully support this project and will aid with the drafting of confidentiality and licensing agreements, leading to further investment and interest in this project.
Based on the results obtained in the project, the PI will secure further funding from national calls (EPRSC or BBSRC) but also from international calls, such as Horizon 2020 and Marie Curie training networks. The PI will also take a leading role in an international training network with our project partners and collaborators, gaining greater exposure on the international stage.